Heat exchangers

ABSTRACT

A heat exchanger comprising one or more planar modules each of which is fabricated from two sheets of metal joined together in face-to-face relationship, the sheets having recesses arranged to form at least two fluid-tight compartments for a first fluid, interconnected by tubes, when the sheets are joined together, the sheet metal between the tubes of each module being louvred to provide heat exchange surfaces over which a second fluid may flow in a direction normal to the plane of the sheets.

United States Patent [191 Fowler Nov. 26, 1974 [5 HEAT EXCHANGERS 3,046,758 7/1962 Heuer et al. .165/170 [75] Inventor: Gordon Fowler, Wantage, England Primary ExaminerCharles Sukalo [73] Asslgnee. 33: 2:21 Lmuted, Berkmg Essex Attorney, Agent, or Firm-Wood, Herron & Evans [22] Filed: Sept. 10, 1973 Appl. No.: 395,383

Foreign Application Priority Data Sept. 8, 1972 Great Britain 41931/72 U.S. Cl. 165/153, 165/166 Int. Cl. F28d 1/02 Field of Search 165/170,171,151, 153,

References Cited UNITED STATES PATENTS 3/1932 Frame 165/170 5 Claims,,5 Drawing Figures "HUVESIHH PATENTEb sum 10F a PATENTEL NDV26I974 SHEET 2 OF 3 wifd PATENTE; mv2 3,850,234

sum 30F 5 22 a 27 /f fif /X 74 HEAT EXCHANGERS module being fabricated from two pressed sheets of metal which are joined together, each pressed sheet having formed therein recesses arranged so that when the two sheets are joined together there is formed two fluid tight header tanks the interiors of which are interconnected by fluid tight tubes extending from one header tank to the other, the sheet metal between the tubes being louvred to provide heat exchange surfaces over which a second fluid may flow in a direction generally normal to the plane of the module.

In the case when there are two or more modules, the heat exchanger may comprise a stack of spaced modules wherein the interiors of each of the header tanks are interconnected by fluid tight connecting pieces to form effectively two sets of header tanks. Preferably the second fluid is constrained to flow through the louvres of the modules in a direction axially along the stack of modules.

The first fluid may be hot or cold liquid, for example hot water derived from the cooling system of a car, in which case the second fluid is air which is constrained to flow through the louvres into the driver and passenger compartments. The air flow may be fan assisted.

The sets of slats of each louvre of the sheet when assembled together may be aligned with one another or may be displaced relative to one another.

A specific construction of a heat exchanger in accordance with the present invention for use in a car air conditioning system will now be described, by way of an example, with reference to the accompanying drawing in which,

FIG. 1 shows schematically a heat exchanger comprising a plurality of interconnected generally planar modules,

FIG. 2 shows a side elevation of one of the modules of the heat exchanger of FIG. 1,

FIG. 3 is a view of the module shown in FIG. 2 looking in the direction of arrow B,

FIG. 4 is a cross-sectional view along line XX of FIG. 3,

FIG. 5 is a sectional view of part of the louvre of the module shown in FIGS. 2 to 4 taken along line YY of FIG. 3.

Referring specifically to FIG. 1 the heat exchanger comprises a plurality of generally planar modules which are arranged in a stack along a common axis to form a generally rectangular block. The heat exchanger has an inlet port 11 through which hot water from the cooling system of the car is admitted to the interior of the heat exchanger, and an outlet port 12 through which the water returns to the cooling system of the car. Air to be heated flows into the passenger compartment of the car through the stack in the direction of arrow A.

Each module 10 is fabricated from two pressed sheets of metal (for example copper alloys or aluminum) 13 and 14 which are joined along a seam 15 as will be seen in greater detail from FIGS. 2 and 3.

From FIG. 3 it will be seen that each sheet 13, 14 is pressed with recesses 16a and 17a which when the sheets 13 and 14 are joined together forms two header tanks 16 and 17 respectively. The sheets 13, 14 are also pressed with recesses 18a which form tubes 18 which interconnect the interiors of the header tanks 16 and 17 when the plates 13, 14 are joined together. The sheet metal in the regions 19 are louvred at the same time that the recesses 16a, 17a and 18a are formed by a suitably shaped cutting and pressing tool. The outer periphery 20 of each sheet 13, 14 is not louvred but it is left flat to enable a good fluid tight joint to be achieved subsequently between sheets 13 and 14.

Two holes 21 are cut into the sheets l3, 14 in the region of one of the header tanks 16 and connecting pieces 22 are simultaneously formed. Similarly, a single hole 23 is cut into the metal sheets 13, 14 in the region of the other header tank 17 and a connecting piece 24 is formed.

The connecting pieces 22 of the sheets 13 are female components and, the connecting piece 24 is a male component, but in the case of sheets 14 the connecting pieces 22 are male components and the connecting piece 24 is a female component. In other respects sheets 13 and 14 are identical therefore only two press tools are required to make the two sheets l3, l4 and the complete fabrication of each sheet 13, 14 may be accomplished in one pressing operation.

One comer 25 of the sheets 13, 14 is relieved to allow connecting pipes (not shown) to be connected onto the inlet and outlet ports of the heat exchanger.

To fabricate the heat exchanger shown in FIG. 1 the appropriate number of pairs of sheets 13, 14 are selected (bearing in mind they are identical) and after degreasing all surfaces which are to be joined are tinned and a plate 14 is laid on top of a plate 13 to form one module 10. The stub of the respective male connecting pieces 22 of plates 14 of one module 10 are inserted into the female connecting pieces 24 of plate 13 of an adjacent module; and similarly, the stub of the male connecting piece 24 of plate 13 of one module 10 is inserted into the female connecting piece 24 of an adjacent module 10. In this way all the header tanks 16 are connected together by connecting pieces 22 and all the header tanks 17 are conneected together by connecting pieces 24. To complete the construction of the stack of modules, the unoccupied connecting pieces 22, 24 of the sheets 13, 14 at the end of the stack can be blanked off by blanking plated 26.

The complete loosely assembled stack of modules 10 is then placed in an oven and a light end load is applied to the stack. The stack is heated to effect brazing or soldering of all the previously tinned surfaces.

From FIG. 1 it will be seen that half the stack of modules is arranged to be inverted relative to the other half i.e., in one half the relieved comers 25 are at the top edge of the stack whereas for the remainder of the stack the relieved corners 25 are at the bottom edge of the stack. This arrangement allows easy connection of the connecting pipes (not shown) onto the appropriate connecting pieces 22 or 24 of one of the modules.

The louvres in each of the sheets maybe arranged so that the slats 27 of sheet 13 are in line with the slats 27 in sheet 14 or, as is preferred, with the slats 27 of sheet 13 displaced axially relative to the slats 27 in sheet 14 as illustrated in FIG. 5. By ensuring the slats 27 of sheet 13 are displaced i.e., in line with the gaps 28 of sheet 15 one obtains a higher efficiency of heat transfer as the air weaves through the louvres. A disadvantage, however, is that more than one press tool is required; one for pressing plate 13 and one for pressing sheet 14.

Instead of making almost identical sheets 13 and 14 one may make sheets 13 as distinct left or right-hand forms providing the mating surfaces of the header tanks 16 and 17 and tubes 18 mate properly when assembled.

Although blanking plates 26 have been suggested above to blank off the end sheets 13 and 14, one could make special end plates which do not require blanking off and substitute the special end plates for the last plate 13 or 14 of the stack of modules.

The header tank 17 may have two holes 23 and two connecting pieces formed in a similar manner to header tank 16.

The connecting pieces 22 and 24 need not be formed in the sheets 13 or 14 in which case separate connecting tubes may be brazed into the holes 21 and 23. However, such a modification complicates manufacture and may not be the best way of connecting the header tanks 16, 17 of adjacent modules.

The heat exchanger described above is not only suitable as a heater for use in air conditioning systems of cars, but could also be used as a cooler or refrigerator for air conditioning systems. In this latter case the first fluid could be a cold liquid or gas and the second fluid would be air fed into the passenger compartment.

The heat exchanger may be used in applications other than air conditioning for automobiles.

What we claim is:

1. A heat exchanger comprising a plurality of planar modules disposed in side-by-side parallel relation one to the other, each of said modules being defined by a pair of metal sheets joined together in face-to-face relationship,

' a header tank formed by and between each pair of sheets at each end of. each module, each header tank being a fluid-tight compartment for a first fluid,

a plurality of tubes in each module formed by and between the pair of sheets that define said module, said tubes interconnecting those header tanks at opposed ends of said module to permit flow of said first fluid between each modules header tanks, connecting means integral with each header tank of each module, said connecting means defining a port in its associated header tank, and the connecting means of one module being connected to the connecting means of an adjacent module to join corresponding header tanks of adjacent modules, thereby permitting flow of saidfirst fluid between modules, and

louvers in each module to provide heat exchange surfaces over which a second fluid may flow in a direction normal to the plane of said modules.

2. A heat exchanger as set forth in claim 1, said connecting means including a connector piece formed from each of those sheets that define said module, said connector pieces defining ports in that area of those sheets that define the associated header tanks, each of said modules thereby being fabricated solely from said pair of metal sheets.

3. A heat exchanger as set forth in claim 2, said connecting means further including a male lip formed on one connector piece of each header tank and a female lip formed on the other connector piece of each header tank, thereby permitting the connector pieces or adjacent modules to be easily joined together in fluid-tight relation.

4. A heat exchanger as set forth in claim 1 in which the second fluid is air which is forced through the louvers of the sheets by means of a fan.

5. A heat exchanger as set forth in claim 1 in which the louvers of adjacent sheets are staggered so as to provide a tortuous path for the second fluid. 

1. A heat exchanger comprising a plurality of planar modules disposed in side-by-side parallel relation one to the other, each of said modules being defined by a pair of metal sheets joined together in face-to-face relationship, a header tank formed by and between each pair of sheets at each end of each module, each header tank being a fluid-tight compartment for a first fluid, a plurality of tubes in each module formed by and between the pair of sheets that define said module, said tubes interconnecting those header tanks at opposed ends of said module to permit flow of said first fluid between each module''s header tanks, connecting means integral with each header tank of each module, said connecting means defining a port in its associated header tank, and the connecting means of one module being connected to the connecting means of an adjacent module to join corresponding header tanks of adjacent modules, thereby permitting flow of said first fluid between modules, and louvers in each module to provide heat exchange surfaces over which a second fluid may flow in a direction normal to the plane of said modules.
 2. A heat exchanger as set forth in claim 1, said connecting means including a connector piece formed from each of those sheets that define said module, said connector pieces defining ports in that area of those sheets that define the associated header tanks, each of said modules thereby being fabricated solely from said pair of metal sheets.
 3. A heat exchanger as set forth in claim 2, said connecting means further including a male lip formed on one connector piece of each header tank and a female lip formed on the other connector piece of each header tank, thereby permitting the connector pieces or adjacent modules to be easily joined together in fluid-tight relation.
 4. A heat exchanger as set forth in claim 1 in which the second fluid is air which is forced through the louvers of the sheets by means of a fan.
 5. A heat exchanger as set forth in claim 1 in which the louvers of adjacent sheets are staggered so as to provide a tortuous path for the second fluid. 